a) Field of the Invention
This invention relates to an ultraviolet ray-absorbing type sandwich glass to be used in the front glass of automobile, the window glass of architecture, and the like.
b) Related Art Statement
Polyvinylbutyral resin has hitherto been most commonly used as an intermediate layer of the sandwich glass of this kind. However, polyvinylbutyral resin is thermoplastic, and has several problems in its use as an intermediate layer of sandwich glass. That is, the sandwich glass having an intermediate layer formed of polyvinylbutyral resin has such problems that (1) polyvinylbutyral resin has a relatively low softening point, and hence sliding of glass plates or formation of bubbles occur due to the heat after the glass plates are stuck to the resin; (2) polyvinylbutyral resin is apt to be influenced by moisture, and hence when the resulting sandwich glass is left to stand for a long period of time under a high humidity atmosphere, the resin whitens from the peripheral portion of the sandwich glass, and deteriorates in its adhesive force to the glass; and further (3) the impact fracture resistance of the resin depends on temperature, and the penetration resistance of the sandwich glass decreases noticeably at a temperature higher than room temperature, that is, at a temperature higher than about 30.degree. C.; and other problems.
The inventors have already disclosed a novel sandwich glass completely free from the above described drawbacks by the use of a thermosetting resin, which resin comprises an ethylene-vinyl acetate copolymer resin and an organic peroxide, as an intermediate layer of the sandwich glass in place of the conventional polyvinylbutyral resin (Japanese Patent Laid-open Application No. 57-196,747). However, although this sandwich glass has such several merits inherent to sandwich glass that an impacting substance is difficult to penetrate into the sandwich glass, and hence the sandwich glass has a high safeness, that the broken glass pieces are hardly scattered, and that the sandwich glass is useful for preventing a residence or building from being intruded by a thief or burglar, the sandwich glass is poor in the ability for preventing the burning of furniture, curtain, carpet, tatami (Japanese straw mat) and the like by the ultraviolet ray, which ability is demanded to sandwich glass corresponding to the grade up of building, residence, interior design and the like, that is, the sandwich glass is poor in the ultraviolet ray-absorbing ability, which serves to prevent the discoloration (yellowing) of furniture, curtain, carpet, tatami and the like and to protect the merchandise exhibited in a show window.
The ultraviolet ray-absorbing ability can be generally given to a resin by adding an ultraviolet ray-absorbing agent to the resin, but when an ultraviolet ray-absorbing agent is added to a thermosetting resin, which contains an organic peroxide and is required to have a high adhesion to glass and a high transparency same as that of glass, the resulting resin composition still has problems in the yellowing with the lapse of time due to the presence of the ultraviolet ray-absorbing agent contained therein and in the poor adhesion to glass.
The inventors have further made various investigations and found out that a benzophenone type or benzotriazole type ultraviolet ray-absorbing agent does not hinder the adhesion of a resin containing the agent to glass, and is very low in the yellowing with the lapse of time, and have accomplished the present invention.